Interpretive Summary: Recently, there has been an increased interest in the role of elk in disease transmission to domestic livestock. Most notably, elk are considered reservoirs for brucellosis, Johne's disease, and tuberculosis, each serious pathogens of domestic livestock. Information concerning basic immune responsiveness of elk, however, is lacking. In this study, we examined the immune capacity of cells isolated from elk blood. Although only minor differences between elk cells and those of more characterized species (e.g., cattle pigs, and humans) were detected, we did find that elk immune cells are fully capable of responding to stimulation. The minor differences that were detected are the focus of further studies.

Technical Abstract:
Interest in the role of elk (Cervus elaphus) and other members of the family Cervidae in the transmission of disease-causing organisms to domestic livestock has increased recently. Most notably, elk are reservoirs for Brucella abortus, Mycobacterium bovis, and Mycobacterium avium subsp. paratuberculosis, each serious pathogens of domestic livestock. An understanding of the basic immune responsiveness of elk will aid research efforts to develop methods of preventing and detecting these diseases. This basic information on immune function, however, is lacking. In the present study, peripheral blood mononuclear cells (PBMC) isolated from captive elk were examined for phenotype, lymphocyte subset proliferative capacity, and ability to produce nitric oxide (NO) upon pokeweed mitogen (PWM) stimulation. Although gd TCR**+ cells represented a high percentage of the peripheral blood lymphocyte pool, these cells responded poorly to PWM stimulation. sIgM**+cells (e.g., B cells), conversely, were largely responsive to PWM stimulation. Addition of PWM to PBMC cultures also resulted in a significant production of nitrite, the stable oxidation product of nitric oxide. Similar to other ruminant species, the majority of elk peripheral blood sIgM**+ B cells co-express MHC class II and B-B4, a B cell lineage marker that varies in expression during B cell development. Findings from the present study provide basic information on several parameters of cellular immunity of elk.